The Study On Biodegradation Of DOP In Biological Aerated Filter

Di-n-Octyl Phthalate(DOP) is one of the American and Chinese controlled pollutant in water. DOP is primarily used as a plasticizer in plastic production and also conjuncted with two other C6-C10 phthalate esters to use in the creation of bottle cap liners and conveyor belts, as dyes, catalysts, or initiator carriers and so on. The widespread use of DOP and the fugitive discharge leads to the DOP pollution in the environment. Consequently the experiment employed biological aerated filter(BAF) to study the biodegradable efficient of DOP, which has the advantages of smaller footprints and resistance of high organic load and so on. The study could supply relatively reliable data and the guide of theory.The experimentrestart the BAF used to the biodegradation of DEHP to reseach the efficiency of the biodegradation of DOP in the different operating condition. The following are the concultions: In the operating condition of the test, the biodegradable efficiency of DOP was increased by the augment of the empty bed contact time(EBCT), and the best percent removal was more than 95%; in the different operating condition,the removal of DOP in BAF was mostly took place below the middle of BAF, and the rate of biodegradation decreased with increasing of the height; the impact of EBCT on the biodegradation efficiency of DOP in BAF is larger than temperature and the best operating condition is when the temperature is 25℃and the EBCT is 8h; when the temperature is 25℃and 7℃, the biodegradation reaction of DOP in BAF is respectively S = S0 exp[-(0.0135t + 0.0593t)h](25℃) and S = S0 exp[-(0.0063t 2 + 0.0188t)h](7℃).The biochemical pathway of DOP degradation by BAF was proposed based on the identified degradation intermediates. The results suggest that the biodegration of DOP in BAF is chief byβ-oxidation.First of all, DOP was sequentially transformed to DHP, DBP and DMP byβ-oxidation, secondly DMP was converted to PA through esterification and PA is into TCA cycle through open-loop, finally it produce CO2 and H2O. The results suggest that DOP is a kind of very weak estrogen and although there is some environmental hormone activity in the effluent of BAF because of the existence of some the metabolites and DOP, its activity has decreased.The SEM and terminal restriction fragment length polymorphism technology (T-RFLP)are used to analysis the morphological characteristics and diversity of microorganism in the bottom of BAF. The SEM-images showed that there are lots of microorganisms attached on the ceramsite particles and relatively long food chain, which has bacillus, aureus, protozoa and so on.There are relatively less microbial populations in BAF because the microorganism mainly degradated the waste with DOP. Nine and ten species are detected, Pseudomonas is accounted for 42.2% of the total microorganism, Achromatium is 29.8%, Sphingomonas is 8.1%, Arthrobacter sp.is 5.1% and the others is 13.8%.